1. Field of the Invention
The invention relates to a vehicle integrated-control apparatus and method which is employed in a vehicle including a drive source, and a stepped automatic transmission that is connected to the drive source and that changes the speed ratio in a stepwise manner. The vehicle integrated-control apparatus and method sets the final control target by coordinating the control target primarily set in response to the input of the driver with instructions from various control systems. The vehicle integrated-control apparatus and method causes a drive control system to control the drive source and the stepped automatic transmission based on the final control target.
2. Description of the Related Art
Japanese Patent Application Publication No. JP-A-05-85228 describes a vehicle integrated-control system in which control elements are hierarchically arranged. In the described vehicle integrated-control system, during the process of converting the input of a driver into a predetermined operation mode, at least one control element at a high hierarchical level passes the signal indicating the mode down to control elements at lower hierarchical levels. The lower-level systems are instructed to establish the mode indicated by the control elements at the higher hierarchical level.
In the vehicle integrated-control system described in Japanese Patent Application Publication No. JP-A-05-85228, control systems at higher levels communicate with the control systems at lower levels in order to determine an achievable control-target-range. This avoids situations where the control target finally set by the higher-level control system cannot be achieved by the lower-level systems given the status of, for example, mechanical and control operations.
However, in vehicles including a stepped automatic transmission, the following problem may occur. If the control system at a higher level assesses the achievable control-target-range (e.g. the range of achievable engine torque) of only, for example, an engine control system, when the higher-level control system provides an instruction to achieve an engine torque included in the achievable control-target-range, the higher-level control system cannot determine whether the shift speed needs to be changed to achieve the engine torque. As a result, an instruction to perform the optimum coordination cannot be provided.